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At least 613 records · Page 34Linked to original sources
PubMed1996

The extended transseptal approach in complex mitral valve surgery--evaluation of risks and benefits.

The extended transseptal approach to the mitral valve was used in 32 patients undergoing isolated or combined mitral valve surgery. In all cases exposure of the entire mitral valvular apparatus was excellent. Two patients died of low output within 30 days of surgery. No cause of death was related to the extended transseptal approach. In one early patient reexploration revealed arterial bleeding from the right atrial suture line which was caused by damage to the sinus nodal artery. In 7 patients temporary atrial conduction disturbances occurred which completely resolved within 10 days after responding well to dual-chamber pacing. Temporary ventricular pacing was necessary in two patients with preoperative bradyarrhythmia. In two patients undergoing mitral re-do surgery a permanent ventricular pacer was implanted. The extended transseptal approach offers an excellent exposure of the entire mitral valve both in primary isolated or combined mitral surgery particularly in re-do surgery where the primary standard vertical left atriotomy is impeded or the conventional transseptal approach gives only limited access. Temporary atrial dysrhythmia is not crucial and is easily controlled by short-term dual-chamber pacing.

Arrhythmias, Cardiac↗
PubMed1989

Electrophysiological effects of left ventricular free wall traction in intact hearts.

Transmural multipolar electrodes, sonomicrometers implanted within the left ventricular wall, and cardiac electrical stimulation techniques were used to examine the effect of transient mechanically applied traction to the left ventricular free wall on local electrophysiological properties. Twenty-five open-chest dogs were atrially paced (cycle length 400 ms) followed by insertion of timed premature extrastimuli at left ventricular epicardial pacing sites either in the vicinity of (traction zone) or remote from (nontraction-control zone) the site of left ventricular free wall traction. Electrophysiological recordings were made before and during intermittent left ventricular free wall traction applied in late diastole (rate 25 cm/s; duration 170 ms). In 22 of 25 dogs, application of traction resulted in early local ventricular activation (mean activation advancement 64 +/- 15 ms), altered QRS morphology of the last conducted atrial drive train beat, and a relative prolongation of ventricular refractoriness in the traction zone. Conversely, in the nontraction-control zone, early activation did not occur and refractoriness was unchanged. Alterations in regional myocardial blood flow (assessed by microsphere technique) did not appear responsible for the observed changes. Furthermore, phenol interruption of local sympathetic or combined sympathetic and parasympathetic innervation or verapamil pretreatment had no impact on the mechanically induced electrophysiological changes. Thus, in normal myocardium in situ, regional abnormalities in wall motion may be associated with alterations of local ventricular activation and refractoriness, factors that in the diseased heart could lead to increased susceptibility to arrhythmias.

Animals↗
PubMed2000

[Incidence of atrial fibrillation in paced patients with complete atrioventricular block].

The aim of the study was to evaluate the incidence of chronic AF in patients paced due to complete AV block. The study group consisted of 130 pts (70 F, 60 M), mean age 68.6 +/- 14.3 y in whom pacemakers were implanted in the years 1990-1998 due to III degree AV block. There were 76 pts with VVI, 24 DDD and 30 VDD modes of pacing. Follow-up period was mean. 47.6 +/- 25.9 m (7-110). Chronic AF developed in 25 pts (19.2%). In the VVI group the incidence of AF was significantly higher than in DDD and VDD groups--30.3% vs. 4.17% and 3.33% respectively, p < 0.01. Ventriculo-atrial conduction (VAC) was found in 19 pts (14.6%), but did not correlate with the development of AF. Stroke occurred in 2 pts with VVI pacing and chronic AF. In conclusion, in pts with complete AV block VDD and DDD pacing significantly reduce the incidence of chronic AF as compared to VVI.

Adolescent↗
PubMed1986

Effects of intravenous ajmaline on atrial excitability and conduction in man.

Slow conduction of early extrastimuli and short refractory periods are some of the factors underlying atrial fibrillation in man. In order to study the effect of ajmaline, a class I antiarrhythmic agent, on these variables, we have performed electrophysiologic studies in 13 patients with and without atrial arrhythmias, before and after the intravenous administration of 1 mg kg-1 of ajmaline chlorhydrate. During paced rhythm with a 600 ms cycle length, extrastimuli were applied to the right atrial appendage, and conduction to the low septal right atrium and the coronary sinus were measured. Ajmaline prolonged P wave duration from 111 +/- 15 to 140 +/- 24 ms (P less than 0.001), conduction of baseline stimuli to low septal right atrium from 69 +/- 14 to 95 +/- 21 ms (P less than 0.001) and to coronary sinus from 127 +/- 18 to 165 +/- 29 ms (P less than 0.001). Atrial effective refractory period increased from 207 +/- 23 to 255 +/- 27 ms (P less than 0.001). Maximum conduction delay of early extrastimuli decreased at the low septal right atrium from 43 +/- 22 to 29 +/- 16 ms (P less than 0.25) and at the coronary sinus from 47 +/- 22 to 21 +/- 14 ms (P less than 0.001). These results show interesting electrophysiologic effects of ajmaline on atrial tissue, with reversion of some of the abnormalities underlying atrial fibrillation, and suggest an antiarrhythmic effect.

Ajmaline↗
PubMed1998

Implications and treatment of atrial fibrillation after cardiothoracic surgery.

Atrial fibrillation (AF) is the most commonly encountered arrhythmia that occurs after cardiothoracic surgery. It develops in up to 40% of patients, most frequently in the first few postoperative days. The strongest risk factors for AF are age and male gender. The pathogenesis of this arrhythmia probably involves increased sympathetic activity in the setting of slowed atrial conduction. The development of postoperative AF is associated with an increased morbidity, higher costs, and prolonged hospitalization. The use of prophylactic beta-blockers and procainamide reduces the incidence of AF whereas digoxin, verapamil, and amiodarone appear less effective. Once AF occurs, the mainstay of treatment remains rate control, anticoagulation, and restoration of sinus rhythm.

Adrenergic beta-Antagonists↗
PubMed1998

Signal-averaged P wave: predictor of atrial fibrillation.

Abnormalities of the P wave seen during sinus rhythm are associated with atrial fibrillation and other supraventricular arrhythmias. Intra-atrial conduction delays can be seen on the surface ECG as P wave prolongation, which is more visible with averaging techniques used in advanced recording devices. Averaging followed by amplification after proper filtering of the electrical signal should allow more precise measurements of duration and amplitude of the P wave. Data on reproducibility, filter settings, required number of beats, and precise definitions of onset and offset are dependent largely on the system used, which can be QRS or, preferably, P wave triggered. This explains conflicting data in the literature. It is clear that P wave duration is one of the best predictors of perioperative atrial fibrillation. For paroxysmal forms, the data are less convincing. Root mean square voltages of the P wave can be useful. Combining the P wave duration with other data often improves the diagnostic value of signal averaging. Standardization of the techniques appears to be necessary.

Atrial Fibrillation↗
PubMed2003

Does impaired left ventricular relaxation affect P wave dispersion in patients with hypertension?

OBJECTIVE: P wave dispersion (PD) is considered to reflect the heterogeneous conduction in atria. We investigated whether there was a correlation between the left ventricular (LV) relaxation and PD. METHOD AND RESULTS: Fifty-three hypertensive patients < or =60 years old were divided into two groups: Group A, 27 patients, aged 54+/-5 years with the impaired LV relaxation and Group B, 26 patients, aged 51+/-8 years with normal LV relaxation. The P wave durations were measured in all 12 leads of ECG and PD was defined as the difference between maximum and minimum P wave duration (Pmax-Pmin). Mitral inflow velocities (E and A), E deceleration time (DT), isovolumic relaxation time (IVRT), left atrial and ventricular diameters, and wall thickness of LV were obtained by echocardiography. Clinical characteristics of both groups were comparable. The wall thickness of LV, Pmax, and left atrial dimension were not different in both groups. A velocity was higher (P<0.001), but E velocity (P=0.03) and E/A ratio (P<0.001) were lower in group A than in group B. IVRT and DT were also significantly longer in group A. PD was significantly higher in group A compared to group B (51+/-9 vs 41+/-11 ms, P=0.01). This difference resulted from the Pmin (61+/-10 vs 67+/-9 ms, P=0.03, respectively). Multivariate analysis revealed a significant correlation between PD and A velocity (r=0.46, P=0.01), E/A ratio (r=-0.53, P=0.001), DT (r=0.65, P<0.001), and IVRT (r=0.73, P<0.001). CONCLUSION: This study suggests that impaired LV relaxation contributes to the heterogeneous atrial conduction in hypertensive patients.

Adult↗
PubMed2001

Classification of electrocardiographic P-wave morphology.

The atrial activity of the human heart is normally visible in the electrocardiogram as a P-wave. In patients with intermittent atrial fibrillation, a different P-wave morphology can sometimes be seen, indicating atrial conduction defects. The purpose of this study was to develop a method to discriminate between such P-waves and normal ones. 20 recordings of each type were used in a classification which, based on impulse response analysis of the P-wave and linear discrimination between various parameters, produced a correct classification in 37 of the 40 recordings (sensitivity 95%, specificity 90%).

Atrial Fibrillation↗
PubMed1999

Conduction disturbances and increased atrial vulnerability in Connexin40-deficient mice analyzed by transesophageal stimulation.

BACKGROUND: Recently, it has been reported that connexin40 (Cx40) deficiency in targeted mouse mutants is associated with a prolongation of P-wave and QRS complex duration on surface electrograms. The specific effects of Cx40 deficiency on sinus node function, sinoatrial, and atrioventricular conduction properties as well as on atrial vulnerability have not yet been investigated systematically by electrophysiological analysis. METHODS AND RESULTS: Fifty-two mice (18 Cx40(+/+), 15 Cx40(+/-), and 19 Cx40(-/-) mice) were subjected to rapid atrial transesophageal stimulation after anesthesia with avertin. A significant prolongation of sinus node recovery time was noticed in Cx40(-/-) mice compared with Cx40(+/-) and Cx40(+/+) mice (287.8+/-109.0 vs 211.1+/-61.8 vs 204.4+/-60.9 ms; P<0.05). In addition, Wenckebach periodicity occurred at significantly longer atrial pacing cycle lengths in Cx40(-/-) mice than in Cx40(+/-) or Cx40(+/+) mice (93. 3+/-11.8 vs 83.9+/-9.7 vs 82.8+/-8.0 ms, P<0.05). Analysis of 27 Cx40(-/-) mice showed a significant increase in intra-atrial conduction time and atrioventricular conduction time compared with 52 Cx40(+/-) and 31 wild-type (Cx40(+/+)) mice. Furthermore, in Cx40(-/-) mice, atrial tachyarrhythmias could be induced frequently by atrial burst pacing, whereas no atrial arrhythmias were inducible in heterozygous or wild-type mice. CONCLUSIONS: This study demonstrates that Cx40 deficiency is associated with sinoatrial, intra-atrial, and atrioventricular conduction disturbances. In atrial myocardium of the mouse, Cx40 deficiency results in increased atrial vulnerability and might contribute to arrhythmogenesis.

Animals↗
PubMed2001

A pilot study to assess the safety of dobutamine stress echocardiography in the emergency department evaluation of cocaine-associated chest pain.

STUDY OBJECTIVE: Chest pain in the setting of cocaine use poses a diagnostic dilemma. Dobutamine stress echocardiography (DSE) is a widely available and sensitive test for evaluating cardiac ischemia. Because of the theoretical concern regarding administration of dobutamine in the setting of cocaine use, we conducted a pilot study to assess the safety of DSE in emergency department patients with cocaine-associated chest pain. METHODS: A prospective case series was conducted in the intensive diagnostic and treatment unit in the ED of an urban tertiary-care teaching hospital. Patients were eligible for DSE if they had used cocaine within 24 hours preceding the onset of chest pain and had a normal ECG and tropinin I level. Patients exhibiting signs of continuing cocaine toxicity were excluded from the study. All patients were admitted to the hospital for serial testing after the DSE testing in the intensive diagnostic and treatment unit. RESULTS: Twenty-four patients were enrolled. Two patients had inadequate resting images, one DSE was terminated because of inferior hypokinesis, another DSE was terminated because of a rate-related atrial conduction deficit, and 1 patient did not reach the target heart rate. Thus, 19 patients completed a DSE and reached their target heart rates. None of the patients experienced signs of exaggerated adrenergic response, which was defined as a systolic blood pressure of greater than 200 mm Hg or the occurrence of tachydysrhythmias (excluding sinus tachycardia). Further suggesting lack of exaggerated adrenergic response, 13 (65%) of 20 patients required supplemental atropine to reach their target heart rates. CONCLUSION: No exaggerated adrenergic response was detected when dobutamine was administered to patients with cocaine-related chest pain.

Adult↗
PubMedDate not supplied

Antiarrhythmic anesthetic action. II. The effect of methoxyflurane on ventricular automaticity.

During the course of surgical anesthesia, the majority of patients experience some arrhythmias, virtually all of which can be attributed to changes in cardiac pacemaker automaticity and/or alterations in cardiac conduction velocity. Therefore, a better understanding of these mechansims is of importance to anesthesiologists. Cardiac automaticity in the intact heart of dogs under methoxyflurane anesthesia was assessed by measuring changes in ventricular escape time (VET) and ventricular escape rate (VER). A slight shortening of VET was noted, while there was virtually no change from control in VER. Unexpectedly, however, a nonsinus supraventricular escape focus became prominent in many animals at a low anesthetic dose and in all animals at a higher anesthetic concentration. This effect was shown to be preventable by pretreatment with reserpine or a beta-blocking agent. It is concluded that methoxyflurane increases the automaticity of parts of the atrial conducting system, other than the sinus, either by a direct effect or by increasing the sensitivity to prevailing background adrenergic levels.

Anesthesia, Inhalation↗
PubMed1988

[Fulguration of foci of atrial tachycardia in the adult].

Fulguration of the site generator of arrhythmia was attempted in three 31, 33 and 55 year-old patients presenting ectopic atrial tachycardias resistant to various antiarrhythmic medications. Episodes of atrial fibrillation and flutter were also documented in two of them. Two patients had a surgically corrected congenital cardiopathy:interatrial communication or pulmonary stenosis. Mapping of the endocardial emergence point was carried out with electrodes placed 1 cm apart, demonstrating the high atrial origin of the tachycardia, near the right atrium. The auriculogram preceded the earliest possible ectopic P wave by 20 to 70 ms; its multiphasic and prolonged morphology, suggested a local intra-atrial conduction disorder in the three cases. Cathodic shocks were delivered at this site without complications with cumulative energies of 720 J, 480 J and 320 J, respectively. The fulguration was ineffective and revealed other arrhythmic sites in two patients. Only patient n1 has been asymptomatic since 24 months under a treatment with Sotalol 160 mg which had been previously ineffective.

Adult↗
PubMed1998

Value of the signal-averaged P wave analysis in predicting atrial fibrillation after cardiac surgery.

Atrial fibrillation (AF) is the most common sustained arrhythmia occurring after cardiac surgery. Beside important implications regarding patient recovery, AF has been shown to substantially lengthen hospital stay--our recent study found a 3-day prolongation after adjusting for all other significant factors. Identification of those at highest risk of AF by clinical or noninvasive characteristics may be a useful strategy for targeted prophylactic therapy. Our data have shown that prolonged atrial conduction as assessed by analysis of the P wave duration from the signal-averaged electrocardiogram (SAECG) imparts a four fold increase in risk for postoperative AF, independently of other measured variables. In addition, abnormal conduction was present on the preoperative P wave ECG (P-SAECG), implying a preexisting substrate that is triggered by surgery. The use of combination abnormal noninvasive variables (eg, abnormal P-SAECG and low left ventricular ejection fraction) can identify groups with a 50% risk of AF, which is nine times as high as when both tests are normal. Thus, the P-SAECG is a useful and accurate predictor of AF after cardiac surgery.

Atrial Fibrillation↗
PubMed2001

Increased incidence of atrial flutter associated with the rejection of heart transplantation.

Atrial fibrillation (AF) and atrial flutter (Afl) are common dysrhythmias that occur after orthotopic heart transplantation (OHT); however, their etiology and clinical significance have not been defined. To determine the precise incidence of sustained AF and Afl and their association with cardiac rejection, 892 consecutive patients who underwent OHT were studied. A total of 104 patients had 113 episodes of Afl; 102 patients had 117 episodes of AF. The incidence of Afl (12.7%) was the same as AF (13.1%). Sixty-nine AF episodes occurred in first 2 weeks after transplantation, and 22 of which were associated with rejection. In contrast, only 20 Afl episodes occurred the first 2 weeks after OHT, 10 of which were associated with rejection. Fifty-two episodes of Afl occurred during from the third week to 6 months after transplantation, 34 of which were associated with moderate to severe cellular or humoral rejection and/or transplant coronary artery disease (TCAD). All 41 Afl episodes that occurred 6 months after transplantation were associated with cellular and humoral rejection, and/or TCAD. The prevalence of Afl was significantly higher in biatrial than bicaval anastomosis. Atrial conduction defect, manifested by the increase of terminal force of the P wave in lead V(1) of the surface electrocardiogram, predicted the occurrence of Afl and AF associated with rejection in OHT with a sensitivity of 89% and specificity of 92%. These results demonstrate that the incidence of Afl increased after OHT, which might be a consequence of cellular and humoral rejection, and coronary vasculopathy of the transplanted hearts.

Adolescent↗
PubMed1985

[Predictive value of the ajmaline test in dysfunction of the sinus node. Prospective 4-year follow-up relative to 77 patients].

To establish the usefulness of Ajmaline test for the evaluation of sinus node function, 77 pts (47 M, 30 F, mean age +/- SD = 61 +/- 15 yrs) first underwent an electrophysiologic study and then were followed-up for a mean period of 46.3 months. The following parameters were determined before and after i.v. administration of Ajmaline (1 mg/kg in 1 minute): sinus cycle length (SCL), corrected sinus node recovery time (CSNRT) and sino-atrial conduction time (SACT). The pts were divided into 3 groups: Group A: 10 pts without clinical or electrocardiographic signs of sinus node dysfunction (SND) and with normal control CSNRT and SACT (less than or equal to 500 and less than or equal to 120 msec, respectively); Group B: 46 pts with clinical-electrocardiographic signs of suspected or apparently not severe SND (sinus bradycardia greater than or equal to 40 beats/min and/or syncopes with positive vagal manoeuvres) and/or slightly abnormal control CSNRT (greater than 500 less than or equal to 600 msec) and/or SACT (greater than 120 less than or equal to 150 msec); Group C: 21 pts with clinical-electrocardiographic signs of apparently severe SND (sinus bradycardia less than or equal to 39 beats/min, sino-atrial block, sinus arrest) and/or definitely prolonged control CSNRT and/or SACT (greater than 600 and greater than 150 msec, respectively). The Ajmaline test was considered negative for the presence of a severe SND if SCL was not prolonged after the administration of the drug more than 20% and CSNRT and SACT were not prolonged more than 50% compared to the control values. Otherwise the Ajmaline test was considered positive. Twenty-seven out of the 77 pts studied underwent permanent pacemaker implantation (23 immediately after the electrophysiologic study and 4 during the follow-up). The following results were obtained: the Ajmaline test was negative in 100% of group A, 87% of group B and 48% of group C pts and positive in 0% of group A, 13% of group B and 52% of group C pts; during the follow-up a negative test resulted predictive in 56 out of 60 pts (92%) and a positive test in 16 out of 17 pts (94%). The predictive accuracy of the test was, therefore, 93.5%. These results indicate that Ajmaline test is an useful provocative test for disclosing, during electrophysiologic studies, pts who have severe SND and for selecting those who need pacemaker implantation.

Adolescent↗
PubMed1999

[Modern therapy of paroxysmal supraventricular tachycardia].

Paroxysmal supraventricular tachycardia (SVT) may have numerous electro-physiologic mechanisms. The most common type of SVT is AV-nodal reentry tachycardia (60%) followed by the bypass tract-mediated SVT (preexcitation. 30%) and a smaller group (10%) comprising paroxysmal atrial flutter or fibrillation and atrial ectopic tachycardia. In persons with otherwise normal hearts symptoms are usually mild and include palpitations or an uneasy feeling in the chest. But some describe precordial pain. Weakness, dizziness, nausea, vomiting, and even syncope. Whenever possible a 12-lead-ECG during an episode of SVT should be obtained. If not possible the use of several Holter-ECG or of an event-recorder may be helpful. Conversion of a SVT can be accomplished by vagal maneuvers or intravenous adenosine (6-18 mg bolus injection). Further diagnostic procedures should prove or rule out a significant structural heart disease. Therapeutic options (expectative, pharmacological prophylaxis, invasive electrophysiologic testing and catheter-mediated modification or ablation) are chosen according to the objective threat (e.g. ventricular fibrillation due to 1:1 conducted atrial fibrillation in a preexcitation syndrome) and the subjective complaints. Definitive healing of the AV-nodal reentry tachycardia and the bypass tract-mediated SVT can be achieved by use of catheter-mediated modification or ablation in 95 to nearly 100%.

Diagnosis, Differential↗
PubMed2003

Atrial fibrillation and electrical remodeling: the potential role of inflammation and oxidative stress.

Atrial fibrillation (AF) represents the most common arrhythmia encountered in clinical practice. The pathophysiology of AF is complex, but in most cases it may be caused by multiple random re-entering wavelets. As generally known, the development of AF leads to electrophysiological and cellular changes in the atria that tend to sustain AF, a process known as electrical remodeling. In addition, it has been proposed that electrical remodeling contributes to the high incidence of early recurrence of AF after cardioversion. The principal characteristics of this process are the shortening of the refractory period with increased dispersion, the loss of rate adaptation, and the reduction of atrial conductivity. On the molecular level, calcium accumulation in myocytes seems to trigger electrophysiological changes leading to reduction in the intensity of L-type calcium current. Currently, the role of inflammation and oxidative stress on electrical remodeling is under investigation. C-reactive protein (CRP), a major inflammatory marker, has been found to be increased in both persistent and paroxysmal AF. Additionally, CRP may have prognostic significance regarding successful cardioversion of AF, and may predict recurrences of arrhythmia. On the other hand, it has been demonstrated that increased oxidative damage occurs in the atria of AF patients and may contribute to electrical remodeling. Interestingly, a prodromal antioxidant intervention study showed beneficial effects from vitamin C on incidence of postoperative AF. The role of inflammation and oxidative stress in AF deserves further study, since amelioration of atrial electrical remodeling by conventional antiarrhythmics has been proved ineffective.

Action Potentials↗
PubMed1994

Plasma levels of natriuretic peptides during ventricular pacing in patients with a dual chamber pacemaker.

The mechanism(s) responsible for the release of brain natriuretic peptide (BNP), a cardiac hormone of ventricular origin, are still not completely understood. We measured plasma atrial natriuretic peptide (ANP) and BNP in 15 subjects (10 men, mean age 67 +/- 3 years) with a dual chamber pacemaker and unimpaired heart function during ventricular pacing, which is known to induce an increase in atrial pressure and plasma ANP concentration. Under ECG monitoring, all subjects received sequential atrioventricular pacing for 30 minutes and ventricular pacing for 30 minutes, at the same rate of 80 beats/min. Arterial pressure and plasma BNP and ANP levels were measured every 10 minutes throughout the study. Ventricular pacing led to atrioventricular dissociation in eight subjects and to retrograde ventriculo-atrial conduction in seven. Arterial pressure remained unchanged in all subjects. In the group with atrioventricular dissociation, plasma ANP increased from 10.14 +/- 0.58 to 16.72 +/- 0.92 fmol/mL at the 60th minute (P < 0.0001), whereas plasma BNP did not change at all (from 1.26 +/- 0.07 to 1.16 +/- 0.09 fmol/mL). In the group with retrograde conduction, plasma ANP concentration doubled (from 10.95 +/- 1.66 to 21.40 +/- 1.51 fmol/mL, P < 0.0001), BNP increased 1.5-fold (from 1.16 +/- 0.06 to 1.64 +/- 0.14 fmol/mL, P < 0.001), and the ANP:BNP ratio augmented from 10:1 to 13.4:1. These results indicate that the release of ANP and BNP is regulated by different mechanisms, supporting the view that there is a dual natriuretic peptide system, comprising ANP from the atria and BNP from the ventricles.

Aged↗